Golf club head

ABSTRACT

An exemplary golf club head having an increased amount of discretionary mass may be realized by utilizing improved drop angles, an improved average crown height, and/or articulation points. The discretionary mass may be placed low and deep in the club head to improve the location of the center of gravity as well as the inertial properties. A preferred break length may also be utilized to further improve the depth of the center of gravity. In one example, the center of gravity may be positioned to substantially align the sweet spot with the face center of the club head.

RELATED U.S. APPLICATION DATA

This is Continuation of application Ser. No. 12/840,771 filed on Jul.21, 2010, which is a Continuation of application Ser. No. 12/332,998filed on Dec. 11, 2008, which is a Continuation of application Ser. No.11/717,107 filed on Mar. 13, 2007 (now U.S. Pat. No. 7,500,926), whichclaims priority of Provisional application No. 60/876,537, filed on Dec.22, 2006.

The disclosure of each related application is hereby incorporated byreference in its entirety.

BACKGROUND

As technology has progressed, wood-type club heads have evolved from therelatively small persimmon-wood heads to the “oversized” metal clubheads typically found in most modern drivers. Despite the changes insize and materials over the years, modern drivers have failed toovercome certain shortcomings historically associated with traditionalwood-type clubs.

For a golfer to extract maximum performance from a golf club, a clubhead having a mass in the range of 180-250 g is generally provided. Acertain portion of the club head's mass is reserved for components thatprovide structural support. The remaining mass, referred to asdiscretionary mass, may be strategically distributed within the clubhead to improve the head's inertial properties and to orient the CG in adesired location.

In conventional drivers, favorable placement of the CG and enhancementof the moments of inertia (MOI) are limited by the available amount ofdiscretionary mass. Conventional methods of increasing the discretionarymass, e.g. thinning the club head walls and utilizing light-weightmaterials, have yielded relatively small gains in availablediscretionary mass. Conventional drivers have generally failed torealize CG locations and moments of inertia necessary to deliverimproved performance due to limited amounts of attainable discretionarymass.

Generally, golfers have a natural tendency to strike the golf ball aboutthe face center of the club head. The face center, in most drivers, isthe point on the face where maximum energy transfer occurs at ballimpact and is also known as the Coefficient of Restitution (COR) “hotspot”. Although ball impact at the COR “hot spot” yields addedperformance benefits in the form of increased distance, it does notnecessarily produce the most accurate ball flight if the COR “hot spot”is not aligned with the impact point on the club face where no headrotation or gear effect occurs, also known as the “sweet spot”, which isthe orthogonal projection of the club head's center of gravity (CG) ontothe striking face of the head. In currently available club heads, the“sweet spot” is generally located above the COR “hot spot” due to thehigh location of the club head's center of gravity. This unfavorable CGorientation produces a club head where only one of these performancevariables, i.e., distance associated with the COR “hot spot” or accuracyassociated with the “sweet spot”, may be maximized during a single golfshot.

Furthermore, this high “sweet spot” location on the face produces astatistically unfavorable ball contact pattern that results in decreaseddirectional shot consistency. The natural tendency of the golfer tostrike the ball about the face center, on average, results in a largerthan desired distance between the location of the ball at impact and the“sweet spot”. This increased distance exaggerates both the head rotationand gear effect of the club head, causing a loss of carry distance andaccuracy.

Shot accuracy and distance are also affected by the depth of the CGrelative to the club face. In modern drivers, the CG is typicallypositioned near the face. This shallow CG placement prevents the clubhead from dynamically flexing the shaft toward alignment with the CG toloft the head and to close the face at impact with the ball.Additionally, a shallow CG decreases the radius of rotation of the faceon off-center hits, thus decreasing shot accuracy.

SUMMARY

Hence, a need exists for a golf club head that provides an increase indiscretionary mass, lowers the CG in the club head, increases the depthof the CG in the club head, aligns the CG with the center of the face,and improves the MOI of the club head.

Such benefits may be attained by utilizing drop angles, recovery angles,average heights, and break lengths in accordance with the embodiments ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of an exemplary golf club in accordance withone aspect of the present invention.

FIG. 1A is a front elevational view of the golf club head of FIG. 1.

FIG. 1B is a front perspective view of the golf club head of FIG. 1.

FIG. 1C shows a template for locating the face center of a golf clubhead.

FIG. 2A shows a horizontal jig plate.

FIG. 2B shows the golf club head of FIG. 1 installed on the horizontaljig plate.

FIG. 2C is a front elevational view of the golf club head of FIG. 1.

FIG. 3 is a front elevational view of the golf club head of FIG. 1.

FIG. 3A is a front perspective view of the golf club head of FIG. 1.

FIG. 3B is a top plan view of the golf club head of FIG. 1

FIG. 3C is a heel side elevational view of the golf club head of FIG. 1.

FIG. 4 is a heel side elevational view of the golf club head of FIG. 1.

FIG. 5 is a front elevational view of the golf club head of FIG. 1.

FIG. 6 is a heel side cross-sectional view of the golf club head of FIG.1.

FIG. 6A is a heel side cross-sectional view of the golf club head ofFIG. 1 and a second exemplary golf club head in accordance with anotheraspect of the present invention.

FIG. 7 is a heel side cross-sectional view of the golf club head of FIG.1.

FIG. 7A is a heel side cross-sectional view of the golf club head ofFIG. 1 and a second exemplary golf club head in accordance with anotheraspect of the present invention.

FIG. 8 is a front elevational view of the golf club of FIG. 1.

FIG. 9 is a front elevational view of the golf club head of FIG. 1.

FIGS. 10A-E illustrate a plurality of non-arcuate junctions inaccordance with another aspect of the present invention.

FIG. 11A is a heel side cross-sectional view of an exemplary golf clubhead in accordance with another aspect of the present invention.

FIG. 11B is a front elevational view of the golf club head of FIG. 11A.

FIG. 11C is a heel side cross-sectional view of an exemplary golf clubhead in accordance with another aspect of the present invention.

FIG. 11D illustrates a non-arcuate junction of FIGS. 10A-E.

FIG. 11E is a heel side cross-sectional view of the golf club head ofFIG. 11C.

FIG. 12 is a top plan view of the golf club head of FIG. 1

FIG. 13 is a front elevational view of the golf club head of FIG. 1.

FIG. 14 is a heel side cross-sectional view of the golf club head ofFIG. 11A.

FIG. 15 is a heel side cross-sectional view of the golf club head ofFIG. 11A.

FIG. 16 is a heel side elevational view of the golf club head of FIG.11A.

DESCRIPTION

Referring to FIGS. 1 and 1A, “reference position,” as used herein,denotes a position of the club head 101 where the hosel centerline 102is in an imaginary vertical plane 104 and is oriented at a lie angle αof 60° with respect to a ground plane 108. The imaginary vertical plane104 is oriented parallel to the top edge 107 of the face 106. Thereference position may be determined in accordance with the UnitedStates Golf Association and R&A Rules Limited, “Procedure for Measuringthe Club Head Size of Wood Clubs,” Revision 1.0, Sections 6.0.1, 6.6, &6.7 (Nov. 21, 2003). Unless otherwise indicated, all parameters arespecified with the club head 101 in the reference position.

Referring to FIGS. 1, 1A, and 1C, “face center,” e.g., face center 112,as used herein, may be located using the USGA method described in theUnited States Golf Association's, “Procedure for Measuring theFlexibility of a Golf Club head,” Revision 2.0, Section 6.1 (Mar. 25,2005). As described in the Procedure for Measuring the Flexibility of aGolf Club head, the face center 112 may be located using a template 113,having a coordinate system with a heel-toe axis orthogonal to asole-crown axis. An aperture 119 may be located at the origin of thecoordinate system and each axis may be divided into evenly spacedincrements. The template 113 may be composed of a flexible material,e.g., a transparent polymer. The template is used as follows:

-   -   (1) The template 113 is placed on the striking surface 111 with        the heel-toe axis substantially parallel to the leading edge        107. The template is then moved back and forth in the heel-toe        direction along the striking surface 111 until the heel and toe        measurements at the opposite edges of the striking surface 111        are equal.    -   (2) The template 113 is moved back and forth in the sole-crown        direction along the striking surface 111 until the sole and        crown measurements at the opposite edges of the striking surface        111 are equal.    -   (3) The template 113 is moved with respect to the striking        surface 111 as described in steps 1 and 2, above, until the heel        and toe as well as the sole and crown measurements along the        corresponding axes are equal. A circle is then marked on the        face via the aperture 119 to indicate the face center 112.

Referring to FIG. 1B, for purposes of determining moments of inertia(MOI) of a golf club 101 according to the various embodiments of theinvention, a three-dimensional coordinate system having axes x, y, andz, has its origin at the center of gravity CG of the club head 101 withthe club head 101 in the reference position. The Z-axis extends throughthe CG generally parallel to the strike face 106 in a vertical directionrelative to the ground plane 108. The Y-axis extends through the CGsubstantially parallel to the strike face 106 and perpendicular to thez-axis. The X-axis extends through the CG and is perpendicular to the Zand the Y-axes. The relevant MOIs may be determined as follows:

-   -   (1) The MOI about the z-axis (I_(zz)) may be determined using        the method described in United States Golf Association and R&A        Rules Limited, “Procedure for Measuring the Moment of Inertia of        Golf Club heads,” Revision 1.0 (Apr. 12, 2006). As described in        the USGA Procedure for Measuring the Moment of Inertia of Golf        Clubheads, a measuring instrument (not shown) designed for        determining the moment of inertia of test parts having mass        properties and overall dimensions similar to that of a golf club        head, may be used to obtain the moment of inertia I_(zz) about        the z-axis. Referring to FIGS. 2A and 2B, a horizontal jig plate        120, described in the USGA Procedure for Measuring the Moment of        Inertia of Golf Clubheads, is attached to the measuring        instrument (not shown), such that the jig plate and the        measurement instrument are level.        -   As shown in FIG. 2A, the jig plate 120 has a first side 121            and a second side 123. The first side 121 includes mounting            pins 125 and the second side 123 includes mounting pins 127.            Pins 125 and 127 comprise rows arranged longitudinally with            respect to the jig plate and columns arranged transversely            with respect to the jig plate.        -   For purposes of measuring the MOI of the club head 101 about            the z-axis, an adapter 118 a (FIG. 2B) is utilized to orient            the club head with respect to the jig plate 120 so that the            sole portion 109 of the club head is facing up and the club            head 101 is disposed such that the angle θ between the hosel            centerline 102 and an imaginary horizontal plane 113 is            substantially 60°. Furthermore, the face portion 106 of the            club head is substantially parallel to the rows of mounting            pins 125 and 127. For purposes of measuring the MOI of the            club head 101 about the z-axis, the pins 125 (FIG. 2A) on            the first side 121 of the jig plate 120 are used for            right-handed club heads and the pins 127 on the second side            123 of the jig plate 120 are used for left-handed club            heads.    -   (2) The MOI about the y-axis (I_(yy)) is determined using a        measurement instrument, e.g, model number MOI-005-104 made by        Inertia Dynamics, Inc. of Collinsville, Conn., designed for        measuring the moment of inertia of test parts having mass        properties and overall dimensions similar to that of a golf club        head. Referring to FIG. 2C, an exemplary measurement instrument        is provided with a horizontal jig plate 120 capable of        accommodating a hosel fixture 118. Proper orientation of the        club head 101 on the hosel fixture 118 is accomplished by        rotating the club head 101, oriented in the reference position,        through 90 degrees so that the toe is pointing upward in the        vertical direction and the CG of the club head 101 is        substantially aligned with the central axis of rotation 114,        which is in the vertical direction, of the measuring instrument.        These measurements are made using methodologies well known to        those skilled in the art.

Referring to FIG. 3, hosel center 122, as used herein, refers to thepoint of intersection between a planar surface 123 and the hoselcenterline 102. The planar surface 123 is characterized by the end ofthe hosel 100.

Referring to FIGS. 3 and 3A, for purposes of locating the CG of a golfclub head 101 according to the various embodiments of the invention, asecond three dimensional coordinate system, including axes X_(hosel),Y_(hosel), and Z_(hosel), has its origin at the hosel center 122, withthe club head 101 in the reference position. Axis Z_(hosel) extendsthrough the hosel center 122 generally parallel to the strike face 106in a vertical direction relative to the ground plane 108. Axis Y_(hosel)extends through the hosel center 122 substantially parallel to thestrike face 106 and perpendicular to the Z_(hosel) axis. Axis X_(hosel)extends through the hosel center 122 perpendicular to the Z_(hosel) andY_(hosel) axes. The CG of the club head may be located as follows:

-   -   (1) Referring to FIG. 3B, the CG is located a first horizontal        distance 124 from an imaginary vertical plane 126. The plane 126        is oriented substantially parallel to the face 106 and passes        through the hosel center 122. The distance 124 is the shortest        horizontal distance from plane 126 to the CG;    -   (2) Referring to FIG. 3B, the CG is located a second horizontal        distance 128 from an imaginary vertical plane 130. The plane 130        is oriented substantially perpendicular to the face 106 and        passes through the hosel center 122. The distance 128 is the        shortest horizontal distance from plane 130 to the CG; and    -   (3) Referring to FIG. 3C, the CG is located a first vertical        distance 132 from the ground plane 108. The distance 132 is the        shortest vertical distance from the ground plane 108 to the CG.

Referring to FIG. 4, sweet spot 134, as used herein, refers to the pointof intersection between the outer surface of the club face 106 and animaginary line 136 that is substantially perpendicular to the face 106and passes through the CG of the club head 101.

Referring to FIG. 5, center apex 138, as used herein, refers to a pointof intersection between an imaginary vertical plane 140 and the top ofthe strike face 106. The plane 140 is oriented substantiallyperpendicular to the face 106 and passes through the face center 112.

Referring to FIG. 6, break length 142, as used herein, denotes ahorizontal distance, at a height 144 relative to the ground plane 108 ina direction substantially perpendicular to the face 106, between animaginary vertical line 146 and the outer surface of a rear portion 148of the club head 101. The imaginary vertical line 146 extends from thecenter apex 138 to the ground plane 108.

Referring to FIG. 7, the term “average height”, as used herein, denotesan average of a plurality of vertical distances, e.g. F₁ . . . F_(n),between a path 174 and the ground plane 108, in a vertical planecontaining the center apex 138 and a rear-most point 149 of the clubhead 101. Vertical distances F₁ . . . F_(n) may be spaced anywherebetween the apex 138 and the point 149 in horizontal increments havingany desired progression, e.g., equal 5 mm increments.

Referring to FIG. 8, face height 154, as used herein, denotes a verticaldistance, with the club head 101 in the reference position, between afirst plane 156, parallel to the ground plane 108 and passing throughthe highest point 160 of the strike face 106, and a second plane 158,parallel to the ground plane 108 and passing through the lowest point162 of the strike face 106.

Referring to FIG. 9, face length 164, as used herein, refers to ahorizontal distance between a heel end 166 and a toe end 168 along ahorizontal plane 170 passing through the face center 112.

The term “non-arcuate junction”, as used herein, refers to a junction oftwo lines where: an endpoint of an arcuate line meets an endpoint of astraight line (FIGS. 10A and 10B), an endpoint of an arcuate line meetsan endpoint of another arcuate line (FIGS. 10C and 10D), or an endpointof a straight line meets an endpoint of another straight line (FIG.10E).

Referring to FIGS. 11A and 11B, articulation point 172, as used herein,denotes at least one point along the path 174 where the curvature of thepath 174 changes from concave to convex or vice versa. The path 174 ischaracterized by the intersection of an imaginary vertical plane 140with the top portion of an exemplary club head 143. As shown in FIG.11B, the imaginary vertical plane 140 is oriented substantiallyperpendicular to the face 106 and passes through the face center 112.Referring back to FIG. 11A, path 174 is laterally bounded by the centerapex 138 and the rear-most point 149. When determining whether the path174 changes curvature, it is assumed that all non-arcuate junctionsalong the path 174 are arcuate. For example, each non-arcuate junction178 of club head 143, illustrated in FIG. 11C, is substituted with animaginary junction 180 having an infinitesimally small radius, as shownin FIGS. 11D and 11E.

Referring to FIG. 12, overall length 182, as used herein, denotes theshortest horizontal distance between a first imaginary vertical plane185, substantially parallel to the strike face 106 and passing throughthe center apex 138, and a second imaginary vertical plane 186 that isparallel to the plane 185 and passes through the rearward most point 149on the club head 101, opposite the strike face 106.

Referring to FIG. 13, overall width 190, as used herein, denotes theshortest horizontal distance between a first imaginary vertical plane192, substantially perpendicular to the strike face 106 and passingthrough the furthest laterally projecting point 196 of the toe 184, anda second imaginary vertical plane 194 that is substantiallyperpendicular to the face 106 and passes through the furthest laterallyprojecting point 198 of the heel 176 having the same height as point196.

Referring to FIG. 14, drop angle β, as used herein, denotes an angleformed by an imaginary vertical line 200 and a line 202 tangent to thepoint of intersection between the line 200 and a path 174. The imaginaryvertical line 200 extends from the path 174 to ground plane 108 at aspecified horizontal distance from the center apex 138, not exceedingthe horizontal distance between apex 138 and point 149. The path 174 ischaracterized by the intersection of an imaginary vertical plane 140with the top portion of the exemplary club head 143. As shown in FIG.14, the imaginary vertical plane 140 is oriented substantiallyperpendicular to the face 106 and passes through the face center 112.Any drop angle β is always measured to the right of the vertical line200 when viewing the club head 143 from a heel side elevational view.

Referring to FIG. 14, recovery angle Φ, as used herein, denotes an angleformed by an imaginary vertical line 200 and a line 202 tangent to thepoint of intersection between the line 200 and the path 174. Theimaginary vertical line 200 extends from the path 174 to ground plane108 at a specified horizontal distance from the center apex 138, notexceeding the horizontal distance between apex 138 and point 149. Anyrecovery angle Φ is always measured to the left of the vertical line 200when viewing the club head from a heel side elevational view.

The term “volume”, as used herein, may be determined using the methoddescribed in the United States Golf Association and R&A Rules Limited,“Procedure for Measuring the Club Head Size of Wood Clubs,” Revision1.0, Section 5 (Nov. 21, 2003). As described in the Procedure forMeasuring the Club Head Size of Wood Clubs, the “volume” is determinedby using the following methodology:

-   -   (1) Water is placed in a container large enough to completely        immerse a club head without the club head touching the        container;    -   (2) The filled container is placed on a digital electronic scale        that is then tared;    -   (3) The club head is slowly lowered into the container until the        top of the club head is just below the surface of the water. The        hosel of the club head should not be submerged;    -   (4) The reading on the electronic scale with the club head        submerged as described in step 3, above, is equal to the actual        volume of the club head in cubic centimeters.

Referring to FIGS. 1-16 and the tables below, exemplary club heads inaccordance with the various embodiments of the present invention areshown and described.

In one aspect of the invention, an improved CG location may be achievedby altering the geometry of the crown, e.g., recessing the crown toincrease the available discretionary mass. This increased discretionarymass may be beneficially distributed within the club head to lower theCG. The amount of discretionary mass obtained as a result ofgeometrically altering the crown may be related to the crown's dropangles (FIG. 14), recovery angles (FIG. 14), average height (FIG. 7),and/or number of articulation points (FIG. 11A). By adapting thesevariables in accordance with the embodiments of the present invention,an increase in discretionary mass may be achieved.

For example, in FIG. 14, an exemplary club head 143 having a crownrecessed toward the ground plane 108 is shown. The crown includes aplurality of drop angles β and recovery angles Φ, i.e. the angles formedby line 200 and tangent line 202 along the path 174 between the centerapex 138 and point 149. This improved crown orientation increases thediscretionary mass of the club head 143 relative to that of aconventional driver, since less mass is required to form the crown. Theamount of discretionary mass created may vary depending on the drop βand recovery angles Φ of the club head. Parameters associated withseveral exemplary embodiments according to the present invention arelisted in Tables 1 and 2, below.

TABLE 1 Drop Angle, Drop Angle, Horizontal Distance Exemplary Exemplaryfrom Center Apex Club Head 1 Club Head 2 2 cm 77.3° 74.3° 3 cm 41.4°47.8° 4 cm 56.7° 58.2° 5 cm 68.4° 63.7° 6 cm 75.3° 68.6° 7 cm 78.9°72.7° 8 cm 81.0° 76.1° 9 cm 82.8° 79.3° 10 cm  80.1° 77.9°

TABLE 2 Recovery Angle, Recovery Angle, Horizontal Distance ExemplaryExemplary from Center Apex Club Head 1 Club Head 2 2 cm 102.7° 105.7° 3cm 138.6° 132.2° 4 cm 123.3° 121.8° 5 cm 111.6° 116.3° 6 cm 104.7°111.4° 7 cm 101.1° 107.3° 8 cm 99.0° 103.9° 9 cm 97.2° 100.7° 10 cm 99.9° 102.1°

In accordance with one aspect of the present invention, club head 143may have a drop angle β, preferably between about 35° and about 87°,more preferably between about 40° and about 85°, and most preferablybetween about 50° and 75°, when measured at a horizontal distancebetween about 2 cm and about 11 cm away from the center apex 138. Inanother aspect, the drop angle β, may be between about 40° and about60°, more preferably between about 50° and about 60°, and mostpreferably between about 41.4° and about 47.8°, when measured at ahorizontal distance between about 2 cm and about 4 cm away from thecenter apex 138. Further, club head 143 may also have a recovery angleΦ, preferably between about 92° and about 145°, and more preferablybetween about 97° and about 140°, when measured at a horizontal distancebetween about 2 cm and about 11 cm away from the center apex 138. Inanother aspect, the recovery angle Φ may be between about 90° and about110°, when measured at a horizontal distance between about 2 cm andabout 4 cm away from the center apex 138. By utilizing drop angles β andrecovery angles Φ in the above recited ranges, an increase indiscretionary mass may be obtained. The increased discretionary mass maybe repositioned low and deep in the club head 143 to improve the CGlocation, resulting in improved shot accuracy and distance.

In another embodiment, shown in FIG. 7A, a club head 101 may utilize anaverage height, i.e. an average of a plurality of vertical distances,e.g. F₁ . . . F_(n), between the path 174 and the ground plane 108,adapted to increase the available discretionary mass. For example, byrecessing at least a portion of the crown toward the ground plane 108and thereby lowering the average height relative to that of aconventional driver, less mass is required to form the crown, thusyielding an increase in discretionary mass. Further, vertical distancesF₁ . . . F_(n) may be spaced anywhere between the apex 138 and the point149 in increments having any desired progression, e.g., 5 mm increments,as shown in Table 3. Parameters associated with several exemplaryembodiments according to the present invention are listed in Table 3.

TABLE 3 Height from Path Height from Path Horizontal Distance to GroundPlane, to Ground Plane, from Center Apex Exemplary Club Exemplary Club[mm] Head 3 [mm] Head 4 [mm] 0 @ center apex 57.1 61.2  5 58.5 62.6 1057.9 62.2 15 57.1 61.3 20 55.2 60.1 25 48.7 54.4 30 42.7 49.5 35 38.645.2 40 35.1 41.9 45 32.6 39.4 50 30.5 36.6 55 28.9 34.4 60 27.7 32.1 6526.4 30.4 70 25.5 28.8 75 24.7 27.3 80 23.8 26.0 85 23.1 24.9 90 22.123.8 95 23.0 100  22.2 Avg. Ht. 37.7 40.4

In accordance with another aspect of the present invention, exemplaryclub head 143 may have an average height, preferably between about 35 mmand about 45 mm, more preferably between about 36 mm and about 41 mm,and most preferably between about 37.7 mm and about 40.4 mm. Theincreased discretionary mass created by utilizing the exemplary averageheights, recited above, may be redistributed in the club head 143 toimprove the mass properties thereof.

In another embodiment of the invention, shown in FIG. 11A, a club head143 including at least one articulation point 172 along a path 174, hasan increased discretionary mass. By utilizing a specified number ofarticulation points 172, a crown shape conducive to a favorable weightdistribution may be achieved. For example, as illustrated in FIG. 11A, arecessed crown 150 may be created by incorporating two articulationpoints 172. The recessed shape of the crown may be adapted to increasethe available discretionary mass by decreasing the mass required to formthe crown. Such weight may be repositioned in club head 143 to increasethe MOI or to place the CG in a more favorable position. This may allowfor a more forgiving club head, resulting in improved shot accuracy anddistance.

Improved placement of the CG may be generally accomplished by depositingthe increased discretionary mass, i.e., the mass obtained by utilizingdrop angles, recovery angles, average heights, and articulation pointsaccording to the embodiments of the present invention, as low and deepas possible in the exemplary club head 143. As shown in FIG. 6,conventional club heads, e.g., club head 101, are limited in theirability to place discretionary weight low and deep due to the geometryof the sole 141. The soles, e.g., sole 141, of conventional club headsare generally elevated with respect to the ground plane 108, whichprevents discretionary mass from being deposited as close as possible tothe ground plane 108. Thus, in another aspect of the invention, shown inFIG. 6A, a sole 139, having the break length 142 near the ground plane108, may be utilized to position the increased discretionary mass as lowand deep as possible in the exemplary club head 143. Parametersassociated with an exemplary embodiment according to the presentinvention are listed in Table 4.

TABLE 4 Vertical distance up from Break Length, Exemplary Club GP [mm]Head 5 [mm.] 1 53.6 2 69.9 3 81.3 4 90.7 5 99.1 6 101.1 7 102.1 8 102.69 103.1 10 103.4 11 103.6 12 103.6 13 103.9 14 103.9 15 103.9 16 103.917 103.9 18 103.9 19 103.6 20 103.1 21 102.6 22 101.3 23 98.3

In some embodiments of the present invention, club head 143 may have abreak length 142 between about 50 mm and about 110 mm at the verticalheight 144 between about 1 mm and about 15 mm relative to the groundplane 108. The break length 142, may be, preferably, between about 90 mmand about 110 mm, more preferably between about 96.5 mm and about 140mm, and most preferably, between about 100 mm and about 130 mm at avertical height 144 between about 5 mm and about 10 mm relative to theground plane 108. The break length 142 in accordance with theembodiments of the present invention, allows discretionary mass to beplaced low and deep within the club head 143, yielding an improved CGlocation.

Referring to FIGS. 4 and 15, in another aspect of the present invention,the increased discretionary mass may be positioned low in the club head143, e.g., by utilizing the break length 142 so that the sweet spot 134is substantially aligned with the COR “hot spot”, i.e., the face center112. By lowering the CG and aligning the sweet spot 134 with the COR“hot spot” 112, the benefits of these performance variables, i.e., theincreased shot distance associated with the COR “hot spot” 112 andincreased accuracy associated with the “sweet spot” 134, may be realizedsimultaneously. Thus, the club head 143, providing improved shotaccuracy and distance, may be achieved.

Referring again to FIG. 15, another aspect of the present invention isto position the discretionary mass deep within the club head 143, e.g.,by utilizing the break length 142, to increase the CG depth, i.e., thehorizontal distance from the CG to the strike face 106. The exemplaryclub head 143, having a CG with such an increased depth, dynamicallyflexes the shaft toward alignment with the CG to loft the head 143 andto close the face 106 at impact with the ball. Additionally, the deep CGof club head 143 may increase the radius of rotation of the face 106 onoff-center hits, thus improving shot accuracy.

CG location coordinates associated with several exemplary embodimentsaccording to the present invention are listed in Table 5.

TABLE 5 Exemplary Exemplary Exemplary CG Location Club Head 6 Club Head7 Club Head 8 First Horizontal 19.6 mm 31.0 mm 28.2 mm Distance SecondHorizontal 62.2 mm 63.0 mm 70.6 mm Distance First Vertical 26.2 mm 27.4mm 28.7 mm Distance

Referring to FIGS. 3B and 3C as well as Table 5, in some embodiments ofthe present invention, first horizontal distance 124 may preferably bebetween about 12 mm and about 38 mm, more preferably between about 15 mmand about 36 mm, and most preferably between about 25 mm and about 35mm. Second horizontal distance 128 may preferably be between about 55 mmand about 78 mm, more preferably between about 58 mm and about 74 mm,and most preferably between about 58 mm and about 66 mm. First verticaldistance 132 may preferably be between about 20 mm and about 33 mm, morepreferably between about 20 mm and about 28 mm, more preferably betweenabout 22 mm and about 30 mm, and most preferably between about 25 mm andabout 30 mm.

In addition to improving the CG location, some discretionary weight maybe repositioned in the face to make the face taller and wider. A largeface, for example, may instill increased confidence in a golfer. Suchimproved confidence may result in increased club head speed, which mayimprove overall ball carry. Furthermore, some discretionary weight mayalso be strategically positioned around the rear portion of the shell.This may increase the MOI about the vertical (I_(zz)) and horizontal(I_(yy)) axes and may ultimately improve performance on off center hitsby reducing slice/hook tendencies.

Table 6 lists moment of inertia, face height, and face lengthmeasurements for several exemplary embodiments according to the presentinvention:

TABLE 6 Mea- Exemplary Exemplary Exemplary sure- Club Head 6 Club Head 7Club Head 8 ment (CH6) (CH7) (CH8) I_(yy) 2486 g · cm² 3149 g · cm² 2866g · cm² I_(zz) 3878 g · cm² 4538 g · cm² 4394 g · cm² Face 49.3 mm 52.6mm 54.6 mm Height Face 101.3 mm 104.9 mm 105.7 mm Length

Referring to FIG. 1B and Table 6, in some embodiments of the presentinvention, I_(yy) may preferably be at least about 2300 g·cm², morepreferably be between about 2300 g·cm² and about 3300 g·cm², and mostpreferably be between about 2700 g·cm² and about 3300 g·cm². I_(zz) maypreferably be at least about 3700 g·cm², more preferably be betweenabout 3700 g·cm² and about 4700 g·cm², or most preferably be betweenabout 3800 g·cm² and about 4600 g·cm².

Referring to FIGS. 8 and 9, as well as Table 6, in some embodiments ofthe present invention, the face height 154 may preferably be betweenabout 43 mm and about 61 mm, more preferably between about 45 mm andabout 58 mm, and most preferably between about 48 mm and about 58 mm.The face length 164 may preferably be between about 94 mm and about 115mm, more preferably between about 96 mm and about 112 mm, and mostpreferably between about 98 mm and about 110 mm.

Referring to FIG. 16, an exemplary golf club 208, shown with thewood-type club head 143, may include a shaft 206, connected to a head143 by a hosel 100. Head 143, may include a hollow shell formed by thestrike face 106 and a body portion 204. The hollow shell may have theheel portion 176, the toe portion 184, the crown portion 150, and thesole portion 141.

Further, head 143 may be formed from a wide variety of materials,including metals, polymers, ceramics, composites, and wood. Forinstance, the club heads of the present invention may be made fromstainless steel, titanium, or graphite fiber-reinforced epoxy, as wellas persimmon or laminated maple. In one exemplary embodiment, club head143 is formed, at least in part, of fiber-reinforced orfiberglass-reinforced plastic (FRP), otherwise known as reinforcedthermoset plastic (RTP), reinforced thermoset resin (RTR), andglass-reinforced plastic (GRP).

In one preferred exemplary embodiment, the body portion 204 may beprovided with the face 106 formed of SP700 Beta Titanium—an alpha/betagrade alloy of 4.5-3-2-2 Titanium (Ti—4.5% Al—3% V—2% Mo—2% Fe). Inalternate embodiments, portions of head 143 may be formed of othertitanium alloys including a forging of a high strength titanium alloysuch as 10-2-3 (Ti—10% V—2% Fe—3% Al) or 15-3-3-3 (Ti—15% V—3% Cr—3%Sn—3% Al), a casting of a 6-4 alloy (Ti—6% Al—4% V), or other titaniumalloys such as 3-2.5 Titanium (Ti—3% Al—2.5% V) or 15-5-3 Titanium(Ti—15% Mo—5% Zr—3% Al). In other embodiments, other forging and castingalloys may be used including stainless steel and aluminum.

In some embodiments, the volume of the club head may be at least about200 cm³, more preferably between about 300 cm³ and about 500 cm³; andmost preferably between about 310 cm³ and about 400 cm³.

A variety of club shafts are contemplated for use with the variousembodiments of the present invention, including the shafts 206 that, forexample, may be made from chrome-plated steel, stainless steel,aluminum, carbon or graphite fiber-reinforced epoxy, boronfiber-reinforced epoxy, or titanium. The shaft 206 may be provided witha grip, for example, formed from molded synthetic rubber or wrappedleather.

In addition, the present invention may relate to a golf club and a setof golf clubs having the inventive golf club heads described herein. Forexample, the set may be a set of wood-type golf clubs which may havemetallic golf club heads.

While various aspects of the present invention are described above, itshould be understood that the various features of the invention may beused singly or in any combination thereof. Therefore, this invention isnot to be limited to only the specifically preferred embodimentsdepicted herein. Further, it should be understood that variations andmodifications within the spirit and scope of the invention may occur tothose skilled in the art to which the invention pertains. Accordingly,all expedient modifications readily attainable by one versed in the artfrom the disclosure set forth herein that are within the scope andspirit of the present invention are to be included as furtherembodiments of the present invention. The scope of the present inventionis accordingly defined as set forth in the appended claims.

The invention claimed is:
 1. A golf club head comprising: a top portion;a rear portion having an outer surface; a strike face comprising anouter surface, a top edge, a face center, and a center apex, wherein thecenter apex is a point of intersection between an imaginary verticaltraversing plane, oriented substantially perpendicular to the strikeface and passing through the face center, and the top edge of the strikeface, the imaginary vertical traversing plane intersecting a point ofthe golf club head that is rearmost in the imaginary vertical traversingplane; a hosel having a hosel centerline, wherein the club golf head isoriented relative to an imaginary horizontal ground plane so that thehosel centerline is in an imaginary vertical hosel plane generallyparallel to the top edge of the strike face, the hosel centerlineoriented at an angle of 60° relative to the imaginary horizontal groundplane; a first imaginary vertical line extending from the center apex tothe imaginary horizontal ground plane; and a first horizontal distance,in a direction perpendicular to the imaginary vertical hosel plane,between the first imaginary vertical line and the outer surface of therear portion of the golf club head, the first horizontal distance beingmeasured at a height between about 1 mm and about 15 mm relative to theimaginary horizontal ground plane and vertically spaced from a rear-mostpoint of the club head, the first horizontal distance being betweenabout 90 mm and about 110 mm.
 2. The golf club head of claim 1 furthercomprising: a center of gravity; and wherein a point of intersectionbetween the outer surface of the strike face and an imaginary lineperpendicular to the strike face and passing through the center ofgravity of the golf club head is substantially coincident with the facecenter.
 3. The golf club head of claim 1, wherein the strike facefurther comprises a face height between about 43 mm and about 61 mm. 4.The golf club head of claim 3, wherein the strike face further comprisesa face length between about 94 mm and about 115 mm.
 5. The golf clubhead of claim 4, wherein the center of gravity located a thirdhorizontal distance between about 12 mm and about 38 mm from theimaginary vertical hosel plane.
 6. The golf club head of claim 5,wherein the center of gravity is located a vertical distance betweenabout 20 mm and about 33 mm from the imaginary horizontal ground plane.7. The golf club head of claim 1 further comprising an imaginarycoordinate system having an origin located at the center of gravity ofthe golf club head, the coordinate system having an x-axis, a y-axis,and a z-axis, wherein the golf club head has a moment of inertia of atleast about 3700 g·cm2 about the z-axis.
 8. The golf club head of claim7, wherein the golf club head has a moment of inertia of at least about2300 g·cm2 about the y-axis.
 9. The golf club head of claim 8, whereinthe center of gravity is located a third horizontal distance betweenabout 12 mm and about 38 mm from the imaginary vertical hosel plane. 10.The golf club head of claim 9, wherein the center of gravity is locateda vertical distance between about 20 mm and about 33 mm from theimaginary horizontal ground plane.